Oxidation of secondary and tertiary alkyl aromatic hydrocarbons

ABSTRACT

COPPER POLYPHTHALOCYANINE WHICH HAS BEEN ACTIVATED BY CONTACT WITH AN AROMATIC HETEROCYCLIC AMINE TO FORM A NOVEL COMPLEX IS FOUND TO BE AN EFFECTIVE CATALYST FOR THE OXIDATION OF SECONDARY AND TERTIARY ALKYL AROMATICS SUCH AS ETHYLBENZENE OR CUMENE TO FORM THE CORRESPONDING HYDROPEROXIDE. THE RATE OF CONVERSION AND THE PERCENTAGE YIELD IS GREATER THAN THAT WITH COPPER PHTHALOCYANINE OR COPPER POLYPHTHALOCYANINE PER SE.

United States Patent O 3,803,243 OXIDATION OF SECONDARY AND TERTIARYALKYL AROMATIC HYDROCARBONS Arthur M. Browustein, Cherry Hill, N.J., andDavid L. Kerr, Wilmington, Del., assignors to Sun Oil Company,Philadelphia, Pa.

No Drawing. Continuation-impart of application Ser. No.

870,732, Sept. 18, 1969, which is a division of application Ser. No.692,685, Dec. 22, 1967, which in turn is a continuation-impart ofapplication Ser. No. 663,234, Aug. 25, 1967, now abandoned. Thisapplication Apr. 21, 1970, Ser. No. 30,607

Int. Cl. C07c 73/06 U.S. Cl. 260-610 B 11 Claims ABSTRACT OF THEDISCLOSURE Copper polyphthalocyanine which has been activated by contactwith an aromatic heterocyclic amine to form a novel complex is found tobe an elfecti-ve catalyst for the oxidation of secondary and tertiaryalkyl aromatics such as ethylbenzene or cumene to form the correspondinghydroperoxide. The rate of conversion and the percentage yield isgreater than that with copper phthalocyanine or copperpolyphthalocyanine per se.

CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of application Ser. No. 870,732, filed Sept. 18,1969, which is a division of application Ser. No. 692,685, filed Dec.22,

1967, which in turn is a continuation-in-part of application Ser. No.663,234, filed Aug. 25, 1967, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a novel catalystand to its use in an improved process for the oxidation of secondary andtertiary alkyl aromatic hydrocarbons such as ethylbenzene, cumene andthe like to form the corresponding hydroperoxide. More particularly,this invention relates to the use of a novel copper polyphthalocyaninecatalyst to improve the oxidation rate of secondary and tertiary alkylgroups on aromatic nuclei to form oxidation products such as a-cumylhydroperoxide.

It is known that cumyl hydroperoxide can be produced very slowly byauto-oxidation when air or oxygen is rapidly passed through cumenewarmed to about 80 C. Also, Canadian Pat. No. 510,517 teaches that therate of oxidation of cumene can be enhanced when carried out in thepresence of alkali or alkaline earth metal oxides or hydroxides, or inthe presence of salts and oxides of heavy metals. Under theseconditions, the conversion rate is only about 2 to 3 percent per hour.In addition, the reaction product contains substantial decompositionproducts such as acetophenone and dimethylphenyl carbinol.

U.S. Pat. No. 2,954,405 teaches the use of copper phthalocyanines ascatalysts in the oxidation of substituted aromatics to form thecorresponding hydroperoxides. However, this process is alsocharacterized by a relatively low hourly conversion rate of about 3 to 4percent. This reference does not teach or suggest the use of copperpolyphthalocyanines as oxidation catalysts.

Soviet investigators, as reported in Dokladi Akademi Nauk SSR, 148, No.1,-pp. 118-121 (January 1963), found that copper polyphthalocyaninewhich was prepared by the reaction of pyromellitic acid or its anhydridewith urea and cuprous chloride in the presence of ammonium molybdatecatalysts, and which was washed with pyridine and dried at 250 C. toremove all impurities, also served as a catalyst for the oxidation ofalkyl aromatics such as cumene to form the corresponding hydroperoxide.However, although the rates obtained by the Russian workers may beinterpreted as being similar to those achieved in the present case, thecause of this apparent catalytic activity cannot be determined, northeir process practiced, in view of the fact that these results couldnot be reproduced when their method of preparing the catalyst wasfollowed.

U.S. Pat. No. 3,300,399 describes the preparation of a copperpolyphthalocyanine by heating pyromellitonitrile in the presence of ametal salt. The resulting material was finely powdered, washed withpyridine, reground and sublimed at a temperature of about 300 C. undervacuum for 24 hours in a manner similar to the Russian process. It isevident from the conditions of this treatment, and from the elementalanalysis, that the residual product represented substantially purecopper polyphthalocyanine containing no pyridine complexed therewith.

SUMMARY OF THE INVENTION It has now been found, in accordance with thepresent invention, that the rate of oxidation of secondary and tertiaryalkyl aromatics to form the corresponding hydroperoxides can besubstantially improved when there is employed a novel oxidation catalystcomprising a copper polyphthalocyanine which has been activated with anaromatic heterocyclic amine such as pyridine.

The novel catalysts employed in this process are formed by combining acopper polyphthalocyanine with an aromatic heterocyclic amine such aspyridine, quinoline, isoquinoline, triazine, pyrazine or the like. Thecatalyst may be prepared in one of several ways, as for example bygrinding the crude, hard, brittle copper polyphthalocyanine to form apowder, washing it with a solvent such as pyridine and ethanol in orderto remove copper salts, thoroughly drying the mixture in a sublimator ata temperature of about 210 to 250 C. for several days in order to removeall volatile impurities, including the pyridine, and then adding ameasured amount of the aromatic heterocyclic amine to the pure copperpolyphthalocyanine to form the novel catalyst.

Alternatively, the catalyst may be prepared by grinding and washing thecopper polyphthalocyanine, using as the solvent the desired aromaticheterocyclic amine itself and then carefully drying the mixture in orderto remove all but a measured amount of the amine solvent. In carryingout this latter process the drying time and temperature are dependentupon the particle size of the copper polyphthalocyanine, the coarserparticles requiring more drying than do the finer particles. In general,drying the ground copper polyphthalocyanine at a temperature of 245 C.for about 96 hours has provided satisfactory results.

The catalyst, when prepared by the first method described above, ispreferably formed in situ by the addition of the heterocyclic amine tothe oxidation reaction medium containing the previously-powdered anddried copper polyphthalocyanine. The reason for this is that when thecopper polyphthalocyanine-amine catalyst is allowed to sit for more thana few months, its effectiveness has been found to be measurablydiminished. This is likewise true when the catalyst is made by othermethods, in which case it is necessary to reactivate the copperpolyphthalocyanine with additional amine before using it.

Regardless of how the catalyst is prepared, it is important that itcontain from about 7 to 200 parts by weight of aromatic heterocyclicamine for each 100 parts of copper polyphthalocyanine, and preferablyfrom 20 to 100 parts. Within these ranges, the particular quantity ofamine employed in activating the catalyst has been found to be somewhatdependent upon the reaction temperature at which the oxidation iscarried out: in general the amount of amine employed may be increased asthe reaction temperature is decreased. Conversely, it is necessary todecrease the amount of amine if higher oxidation temperatures areutilized up to an optimum temperature of about 130 C. Beyond thistemperature, excessive by-products start to form regardless of theamount of amine employed. It has further been found that if the aminecontent is reduced below the ratios set forth above, the activity of thecatalyst is substantially reduced, while an increase in the aminecontent of the catalyst in excess of those of the above range results inextensive decomposition of the desired hydroperoxide product.

In a further embodiment of this invention, it has been found that, mostsurprisingly, after the normal decrease in the activity of the catalysthas taken place with the passage of time, this activity may very readilybe restored to approximately its original level by the addition of theheterocyclic amine directly to the reaction medium, whereupon thecatalytic activity is almost instantaneously restored. Moreover, it hasfurther been found that this restoration may be efiFected many timesduring the life of the catalyst without any substantial loss ofcatalytic activity. The amount of heterocyclic amine which must be addedto restore catalytic activity will naturally vary, depending upon theamount of the copper polyphthalocyanine in the medium, the timeinterval, and the like. Generally, however, it is suflicient if theamine is introduced in amounts not in excess of the weight ratiosemployed in the formation of the original polyphthalo-cyanine-aminecatalyst, and preferably somewhat smaller amounts of amine should beemployed.

While applicants do not wish to be bound by any particular theory, it isbelieved that the reaction product of the copper polyphthalocyanine andthe heterocyclic amine is in the form of a complex of the two componentsrather than a sample admixture. Evidence for this has been adduced bythe fact that catalytic activity rapidly decreases with decreasingheterocyclic amine to copper polyphthalocyanine ratios: whereas incontinuous operations employing initially the preferred amine:polyphthalocyanine ratio, there is no observed decline in catalyticactivity at a point where successive replenishment of the mother liquorwith fresh reactant would have theoretically guished by its ability toincrease the rate of oxidation of secondary and tertiary alkylaromatics, is a solid material at room temperature and is characterizedby its high insolubility in most reaction media.

The copper polyphthalocyanine component of applicants novel catalyst maybe prepared in many different ways, and indeed, depending upon themanner of its preparation, may have different properties andcharacteristics. Thus, for example, the preparation of one form ofcopper polyphthalocyanine, which is formed by the reaction ofpyromellitonitrile with a copper salt such as cuprous chloride, isdisclosed in British Pat. No. 883,552. Briefly, this catalyst may beprepared by various methods, as for example, by reacting an excess ofpyromellitonitrile with finely divided cuprous chloride in an inert,oxygenfree atmosphere, at elevated temperatures of about 300 to 400 C.and elevated pressures of about 2000 to 3000 psi. for several hours.Small amounts of urea may be added, if desired, in order to neutralizeany resulting hydrogen chloride. The resulting material is characterizedby its dark blue color, its graphite-like consistency, and itssubstantial insolubility in most solvents, including sulfuric acid.

Another known form of copper polyphthalocyanine is described in theaforementioned Soviet journal, Doklady Akademi Nauk. The copperpolyphthalocyanine described in that article is prepared by the reactionof pyromcllitic dianhydride with urea and a copper salt such as cuprouschloride, in the presence of ammonium molybdate catalyst, andis notablysoluble in concentrated sulfuric acid. This latter product is furthercharacterized in that its I.R. spectrum shows strong carbonyl bands at5.63 and 5.80 microns, while the copper polyphthalocyanine prepared frompyromellitonitrile shows no carbonyl bands, but does show a weak nitrilegroup at 4.45 microns.

Notwithstanding the differences between these two illustrative forms ofcopper polyphthalocryanine, each of them, when activated by an aromaticheterocyclic amine, forms a catalyst whose activity far surpasses thatof any of its components.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The secondary and tertiaryalkyl aromatic hydrocarbons employed as the starting materials in theprocess of this invention have the following structural formula:

wherein R is lower alkyl; R is lower alkyl or hydrogen; Ar is asubstituted or unsubstituted aromatic nucleus such as phenyl ornaphthyl; and R and R taken together form a cycloalkyl ring having from4 to 7 carbon atoms; and wherein R and R may be the same or differentalkyl groups. The aromatic nucleus may be substituted by such groups aslower alkyl, lower alkoxy, halo, nitro or cyano radicals. Preferably,the secondary or tertiary alkyl aromatic is represented by suchcompounds as cumene or ethylbenzene, although it is understood thatcompounds such as p-diisopropylbenzene, sec.-butylbenzene,isopropylnaphthalene, p-cymene and the like may also be utilized.Moreover, it has been found that this process is equally effective inoxidizing cycloalkyl aromatics such as phenylcyclohexane. Thus, forpurposes of this invention cycloalkyl groups which are substituted for Rand R; taken together, react as tertiary alkyl compounds.

The process of this invention, utilizing the afore-described catalyst,is conveniently carried out by the rapid passage of oxygen or airthrough a suitable reactor, to which has first been added a solution ofthe alkyl aromatic and the copper polyphthalocyanine-heterocyclic aminecatalyst. The air or oxygen should be brought into intimate contact withthe liquid phase, for example, by the use of high speed stirrers,suitable nozzles or the like.

The amount of catalyst employed will vary depending upon the nature andamount of material to be oxidized. In general, however, the amount ofcatalyst may vary from about 0.05 grams to 2.0 grams of catalyst permole of substrate, and preferably should be from 0.1 to 1.0 grams permole of substrate.

The rate of input of oxygen or air will depend upon the temperature andpressure utilized during he oxidation. There should be provided at leastone amount theoretically sufficient to convert the alkyl-substitutedaromatic compound completely to the corresponding hydroperoxide, andpreferably an excess of this amount. It has been found that a flow rateranging from 0.5 to 300 liters per hour is generally sufiicient for mostconversions. Any uncombined oxygen may, of course, be recycled to thereactor. The reaction may be elfected at normal or superatmosphericpressure.

The reaction temperature may range from about to 130 C., but ispreferably in the range of from to C. While it has been found that therate of conversion of substrate to hydroperoxide may initially beincreased at temperatures over about 115 0., this is accomplished onlyat the expense of some of the remaining substrate which is convertedinto unwanted by-products.

The reaction is generally complete in from one to ten hours, dependingupon the amount of substrate employed. It is preferred, however, thatthe reaction be terminated after a period of two to three hours in orderto avoid excessive decomposition of the hydroperoxide, in which caseunreacted starting material is readily recovered and recycled to thereactor. v

Advantageously, small amounts of the hydroperoxide corresponding to thedesired product may be introduced into the reaction medium to act as areaction initiator. Thus, for example, when cumene is being oxidized, ithas been found to be advantageous to add a small amount of cumylhydroperoxide in order to initiate the reaction. As an accelerator theremay also be introduced into the reaction medium alkali metal salts suchas sodium or potassium carbonate, which, it has been found, furtheraccelerates the oxidation of such starting materials asphenyl-cyclohexane. The amounts of these materials to be added are notcritical, but 0.25 to 3 percent by weight of starting material ispreferred.

The resulting hydroperoxide product is readily recovered from thereaction medium by conventional methods. Thus, for example,hydroperoxide may be conveniently recovered by isolating it as itssodium salt by addition of concentrated aqueous NaOH to the reactionproduct.

The hydroperoxides obtained by the process of this invention are highlyuseful in various important commercial applications. Thus, for example,when cumene is oxidized in accordance with the present invention, thereis formed a-cumyl hydroperoxide which, when reacted with an acid such assulfuric acid, is converted to industrially useful phenol and acetone inaccordance with the following reaction.

PREPARATION OF TWO TYPES OF OOPPPER POLYPHTHALOCYANINE (A) Preparationof copper polyphthalocyanine from pyromellitic dianhydride (PMDA) PMDA(184 mmoles), anhydrous CuCl (120 mmoles), urea (3.60 moles) and (NI-LQMoQ; (0.1 g). were intimately blended and heated at 180 to 185 C. for 2hours. The black solid was washed with H O (0.5 l.) and then dissolvedin concentrated H 50 (200 ml.) at room temperature. The dark solutionwas slowly added to cracked ice and water (3 1.). A fine precipitate wasreadily obtained. The solids were filtered and washed with H O until thewashings were neutral. The dried solids were extracted with pyridine,and then dried with a sublimator at 240 C. (0.1 mm. Hg) until solids nolonger appeared on the cold finger. The navy blue product was partiallysoluble in DMF. The IR. spectrum closely resembles thepyromellitonitrile derived compound except for the absence of thenitrile group and the ap pearance of a carbonyl doublet indicative ofanhydride end groups. The strong carbonyl bands suggest a low molecularweight polymer. This lower molecular Weight is supported by thesolubility of the compound in DMF and concentrated H 80 Elementalanalysis for a completely branched structure follows:

Calculated (percent): C=55.7, H=0.93, N=21.7, Cu =l1.6. Found (percent):C=52.1, H=2.02, N=20.7, Cu=6.54. Surface area=7.1 square meters pergram.

(B) Preparation of copper polyphthalocyanine from pyromellitonitrile Aheavy-walled glass tube was charged with pyromellitonitrile (11.0mmoles) Cu Cl (6.5 mmoles) and urea (2.0 mmoles). The mixture wasintimately ground in a mortar before charging. The tube was thoroughlyflushed with helium and sealed. It was heated at 390 C. for 19 hours.The fused, hard, black solid was extracted with pyridine and then washedalternately with ethanol and water until there was no detectable odor ofpyridine or color to the washes. The purple solid was heated in asublimator at 240 C. and 0.1 to 0.5 mm. Hg for several days untilimpurities cease to sublime. The product was a navy blue, metallicpowder. Yield=2.1 g. It was insoluble in all solvents includingconcentrated H at room temperature.

Elemental analysis is in accord with the proposed rectilinear structure.

Calculated (percent): C=55.3, H=0.92, N=29.0, Cu=14.7. Found (percent):C=53.3, H=1.55, N=25.5, Cu=14.1. Surface area of the catalysts is 6.7square meters per gram.

EXAMPLES The following reactions were carried out in a 50 ml. resin potimmersed in a thermostated oil bath. The pot was fitted with a hollowstirrer shaft through which oxygen could be added and dispersed throughthe agitated system. The apparatus was otherwise fitted with awatercooled reflux condenser and vented to the atmosphere through amineral oil or mercury bubbler. Oxygen pressure was maintained at about1 atmosphere by a rapid flow-through of 60 mls./min.

Unless otherwise noted, cumene (200 mmoles) was used with cumenehydroperoxide (1 mole percent) as a promoter and 0.25 weight percent(ca. 0.1 mmoles) catalyst in suspension. Pyridine content was generally57 mg. and except in Examples 1 to 7, it was added to the agitatedsystem (ca. 450 r.p.m.) after all other reagents were present.

The reaction was followed for hydroperoxide formation by removing 0.2ml. aliquots of solution and titrating iodometrically with 0.01 N Na S OFor selectivity studies, the reaction was carried out in a closed flaskfitted to a gas buret. Selectivity was determined by comparing oxygenuptake (conversion) against hydroperoxide production as measurediodometrically.

The selectivity measurements (mole percent) shown in the last column inTables I and H, and mentioned elsewhere represent measurements takenduring the first hour only. For longer periods, it will be understoodthat a decrease in hydroperoxide concentration takes place, whichdecerase follows known kinetics for this type of reaction in that theselectivity of the hydroperoxide drops with lncreasing concentrations ofthis product.

In the following tables and discussions, these abbreviations have beenused:

CuPCCopper phthalocyanine CuPPCCopper polyphthalocyanine Also, incertain of the following tables, where conditions were otherwise thesame, some of the examples have been repeated for sake of comparison.

EXAMPLES 1 t0 7 Table I summarizes the activity of CuPPC prepared frompyromellitonitrile and containing 57 mg. of residual pyridine (i.e. noadditional pyridine has been added to the system) shown in Examples 2, 4and 6, as compared to the activity of CuPC (Examples 1, 3 and 5), NaOH(Example 7) and CuPPC wherein all the pyridine has been removed (Example7A). The very low order of activity during the first two hours of thislatter run will be evident, particularly in comparison with the markedincrease in rate during the third hour, after pyridine was added forsake of this comparison.

TABLE I Reaction time, hrs.

1 2 3 4 Selectivity, Reaction Cumene hydroperoxide, mole Ex. Catalystsystem temp., mole percent of theoretical percent 1 CuPC 80 1. 24 2. 474. 90 6. 00 100 CuPPC plus pyridine-.. 80 2. 30 4. 20 100 Cu 105 2. 503. 75 5. 85 9. 85 100 CuPOC plus pyridine.... 105 9. 68 18. 3 24. 6 32.7100 CuPC 125 9. 50 21. 1 30. 8 43. 1 95. 5 5-. CuPPC plus pyridine 12515. 3 24. 5 35. 7 43. 3 96. 6 7-- Aq. NaOH 130 5. 54 24.6 31.6 42.6 88.27A----" CuPPO 105 0. 81 1. 53 8.

1 Measured during first hour. 1 0.01 ml. percent aq. Na0H/200 rnls. cumne.

e Prepared in accordance with preparation B," page 11 (supra), whereinall pyridine was removed.

56.9 mg. of pyridine added at beginning oi third hour.

EXAMPLES 8-15 Table H illustrates the decline ofCuPPC activity, and itsrestoration by the addition of pyridine. CuPPC used in these reactionsis prepared by pyromellitronitrile. The reactions were all carried outat 105 C.

TABLE II Reaction time, hrs.

1 2 3 4 Selectivity, Reaction Cmnene hydroperoxide, mole Ex Catalystsystem temp, 0 mole percent of theoretical percent 1 8 OuPPC 2 9. 6818.3 24.6 32.7 100 9..-- CuPPC 1.55 1.65 2.40 3. 75 100 P 0. 60 1. 70 l8. 15 CuPPC plus pyridine L 6. 95 16. 6 26. 6 36. 6 100 CuPC pluspyridine 5 1. 85 4. 75 7. 10. 4 100 Cu? 2. 50 3. 75 6.85 9. 85 100 2. 053. 95 B 10. 4 1. 50 1. 60 2. 35 3. 70 100 1 Measured during first hour.

I Freshly prepared sample containing endogenous pyridine (57 mg.). 1Catalyst sample after 4 months shelf life.

4 Addition of pyridine (57 mg.) after 2 hours reaction time.

I Pyridine (57 mg.) added at start of reaction.

0 OuPPG from PMDA added after 2 hours reaction time.

7 CuPPO prepared in accordance with 11.8. Pat. No. 3,300,339.

From the foregoing data, it can be seen that there is no interactionbetween pyridine and CuPC as there is between the former and CuPPC togive enhanced activity. In fact, the similarity in activity between CuPCplus pyridine and pyridine, per se, suggests that CuPc is entirelycoordinated by pyridine and it is the excess base that is catalyzing thereaction. The restoration of CuPPC activity by addition of pyridineduring the third hour of the reaction shows the need of the latter forsuperior activity. This need for pyridine is further demonstrated in thereaction where pyridine and CuPPC are both present initially. Not onlyis selectivity still 100% with the CuPPC-pyridine system, but catalyticactivity is brought back to substantially the same level as initially.

EXAMPLES 16-20 Table IH illustrates the effectiveness of theheterocyclic amine quinoline as compared to other catalyst systems.

ed. 0.01 mi. of 20% sq. NaOH.

The activity of quinoline and pyridine are quite similar, whichindicates that the CuPPC catalytic system is useful with the generalclass of armoatic heterocyclic EXAMPLE 21 An experiment was run todetermine how long a single batch of catalyst could be re-nsed until itsactivity was lost. Toward this end, a reaction was run for a period of 2hours at the end of which one-half the mother liquor was siphoned ofland replaced by fresh cumene. The rate of hydroperoxide production wasfollowed iodometrically. The process was conducted at with CuPPCcontaining pyridine (7:1 mole ratio). The data are summarized in TableIV.

As will be seen from the above data, there was no strong decline inconversion until the seventh cycle at the end of which fresh pyridinewas added. This readily restored the rate to the initial level. 0f theoriginal CuPPC (60 mg.), 51 mg. were recovered. Its 1R. was identical toits original spectra. The loss of 9 mg. is believed to be mechanical.Total production of cumene hydroperoxide was 0.329 mole. Thus, it isevident that the catalyst can be used indefinitely with only the needfor trace addition of pyridine. Only 57 mg. of the latter was used up inthis continuous process.

These data support the conclusion that pyridine forms an insolublecomplex with the catalyst. If this were not the case, activity shouldhave declined sharply by the third cycle as this would have constituteda dilution of soluble pyridine in the amount of about 1:8.

EXAMPLE 22 To a 200 ml. resin pot equipped with a reflux condenser,mechanical stirrer, and inlet for oxygen was added 200 mmoles of cumene,60 mg. of copper phthalocyanine and 2 mmoles of cumyl hydroperoxide.Oxygen was rapidly passed through the system at 60 ml./min. Agitationwas maintained at 400-500 rpm. at a temperature of 105 C. The progressof the reaction was followed by iodometric titration of thehydroperoxide which was produced.

The reaction was then repeated substituting as the catalyst, first,copper polyphthalocyanine prepared from pyro mellitic dianhydride, andthen copper polyphthalocyanine prepared from pyromellitonitrile whichcontained 55 mg. of pyridine. The comparison of the yields of a-cumylhydroperoxide obtained from each of these catalysts was as follows:

Mmoles o! hydroperoxide Reaction time, hours 1 2 3 Catalyst:

gopper ph tha l oz zlyainineu, ..(E mi. 7. 10 14.2 20.0

per po yp t a ocyamne rom pyrome it dride) 6. 46 11.4 17. 48 Copperpolyphthalocyanine-pyridine" 36. 61. 4

Analysis of the reaction product from the latter catalyst revealed thatno by-products were produced and that only a-cumyl hydroperoxide wasobtained.

EXAMPLE 23 Mmoles of hydroperoxide Reaction time, hours 3. 0 4. 5Catalyst:

None (K2003 only) 3.6 4.8 Copper phthalocyanine 11. 3 17. 95 Copperpolyphthalocyanine-triazine 14.2 21. 93

Analysis of the latter reaction medium revealed no other products thanthe desired hydroperoxide.

EXAMPLE 24 Repeating the procedures of Example 22, 200 mmoles ofethylbenzene, 2 mmoles of cumyl hydroperoxide and 60 mg. of copperpolyphthalocyanine from pyromellitic dianhydride were charged to thereactor which was heated at 105 C. while oxygen was passed through thesystem at 60 mL/min.

The above procedure was repeated substituting the pyridine-containingcopper polyphthalocyanine from pyromellitonitrile for the firstcatalyst, which contained no pyridine. The yield of ethylbenzenel-hydroperoxide was found to be as follows:

Mmoles of hydroperoxide Reaction time, hours 3.0 6. 0

Catalyst:

Copper polyphthalocyanine from pyromellltic dienhy de 3.10 4.97 Copperpolyphthaloeyanine-pyridine 4. 50 7. 06

Further analysis of the latter reaction product revealed no otherproducts than the desired hydroperoxide.

EXAMPLE 25 Reaction time, hours: Mmoles, hydroperoxide EXAMPLE 2.6

Repeating the procedures of Example 22, but substitutingS-sec-butylnaphthalene for cumene as the starting material, tenmillimoles of fi-sec-butylnaphthalene hydroperoxide were obtained afterfive hours using CuPPC-pyridine as the catalyst. When CuPC and CuPPCcontaining no pyridine were substituted as the catalysts, only traceamounts of the hydroperoxide were obtained.

It will be seen from the foregoing data that the activity of copperphthalocyanines which have been contacted with aromatic amines remainswholly unaffected whereas the activity of the copper polyphthalocyaninecatalysts which have been activated with aromatic heterocyclic aminesare greatly superior to those other copper phthalocyanine orpolyphthalocyanine catalysts in increasing the reaction rate for theoxidation of secondary and tertiary alkyl aromatics to form thecorresponding hydroperoxides. Thus, as the examples show, conversion tothe hydroperoxide can, in many cases, proceed at more than 9 percent perhour during the start-up period, which is approximately a three-foldgain on a weight basis, over any of the other related catalysts of theprior art.

What is claimed is:

1. A process for the oxidation of secondary and tertiary alkyl aromatichydrocarbon to produce the corresponding hydroperoxide which comprisescontacting said alkyl aromatic hydrocarbon having the structuralformula:

R Rt-C-H i.

in which R is lower alkyl; R is selected from the group consisting ofhydrogen and lower alkyl; R and R taken together form a cycloalkyl ringhaving from 4 to 7 carbon atoms; and Ar is an aromatic nucleus selectedfrom the group consisting of phenyl and naphthyl, with oxygen attemperatures of from about to C. in the presence of a catalystcomprising a copper polyphthalocyanine and an aromatic heterocyclicamine selected from the group consisting of pyridine, quinoline,isoquinoline, triazine and pyrazine, wherein the weight ratio of saidamine to said polyphthalocyanine is between about 0.7:1 and 2:1.

2. The process according to claim 1 wherein the aromatic heterocyclicamine is pyridine.

3. The process according to claim 1 wherein the aromatic heterocyclicamine is quinoline.

4. The process according to claim 1 wherein the weight ratio of aromaticheterocyclic amine to copper polyphthalocyanine is between about 02:1and 1:1.

5. The process according to claim 1 wherein the aromatic heterocyclicamine is added to the reaction mixture containing a partiallydeactivated copper polyphthalocyamine-aromatic heterocyclic aminecatalyst.

6. The process according to claim 1 in which the reaction is carried outin the presence of an added hydroperoxide.

7. The process according to claim 1 in which the reaction is carried outin the presence of an added alkali metal salt.

8. The process according to claim 1 in which the alkyl aromatic compoundis cumene and the hydroperoxide is a-cumyl hydroperoxide.

9. The process according to claim 1 in which the alkyl aromatic compoundis ethylbenzene and the hydroperoxide is ethylbenzcne l-hydroperoxide.

10. The process according to claim 1 in which the alkyl aromaticcompound is phenylcyclohexane and the hydroperoxide is phenylcyclohexyll-hydroperoxide.

11. In the process according to claim 1 for the oxidation of secondaryand tertiary alkyl aromatic hydrocarbons wherein the catalyst employedis copper polyphthalocy- 12 amino activated with an aromaticheterocyclic amine, the step which comprises adding said amine to thereaction medium when necessary in order to maintain the weight ratio ofamine to copper polyphthalocyanine at between 0.07:1 and 2:1.

References Cited UNITED STATES PATENTS 2,734,086 2/1956 Goppel et a1.260-610B 2,954,405 9/1960 Hock 260-610 B 3,300,399 1/1967 Wildi et a1.260-610 R FOREIGN PATENTS 558,506 6/1958 Canada 260-610 B W. B. LONE,Assistant Examiner U.S. C1. X.R.

